The allergic form of asthma is driven by an immune response to airborne allergens, and can be exacerbated by a number of factors including exposure to viruses. A typical signature of disease is the accumulation in the lungs of Th2 lymphocytes, eosinophils, mast cells, fibroblasts, and macrophages. Whereas the acute phase of asthma is characterized largely by rapid cell infiltration in the lungs, chronic asthma is characterized by progressive airway remodeling which includes epithelial cell mucus metaplasia, smooth muscle hypertrophy/hyperplasia, subepithelial fibrosis, and increased angiogenesis. Fibrosis is due to deposition of extracellular matrix proteins such as collagen, fibronectin, tenascin, and laminin, thought produced largely from differentiating fibroblasts or epithelial cells, which can additionally be induced to express alpha smooth muscle actin and contribute to the enhanced smooth muscle mass. How all of these cell types are controlled is largely unknown. This proposal will focus on several members of the tumor necrosis factor (TNF) and TNF receptor superfamily, and test the hypotheses that OX40 (CD134) interacting with OX40L (CD252), and LIGHT (CD258) interacting with two receptors, HVEM (CD270) and LTBR (lymphotoxin beta receptor), are signatures of allergen-induced inflammation and remodeling in lungs of patients with varying severity of asthma; that these molecules will be further induced in the lungs of patients that are exposed to rhinovirus, a pathogen that has been associated with asthma exacerbations; and that they will be functionally relevant to the inflammatory and remodeling activities of bronchial epithelial cells, and lung macrophages, fibroblasts, and T cells. The treatment options for asthmatics are currently limited. Understanding when and where these TNF/TNFR family molecules are expressed, and the functional activities that result from their interactions, might lead to new and novel targets for therapeutic intervention in both acute and chronic asthma.